thermal: core: move tz->device.groups cleanup to thermal_release

The device_unregister call in thermal_zone_device_unregister causes the
thermal_zone_device structure to be freed before the call to free the
dynamically allocated attribute groups. This leads to a kernel panic.

Furthermore, the 4 calls to free the trip point attribute structures
occur before the call to unregister the device, leading to a kernel
panic when sysfs attempts to access the attributes to remove them.

Here is an example of a kernel panic when the cpu thermal zones are
removed upon cpu offline:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: strlen+0x0/0x20
<snip>
Call Trace:
   ? kernfs_name_hash+0x17/0x80
   kernfs_find_ns+0x3f/0xd0
   kernfs_remove_by_name_ns+0x36/0xa0
   remove_files.isra.1+0x36/0x70
   sysfs_remove_group+0x44/0x90
   sysfs_remove_groups+0x2e/0x50
   device_remove_attrs+0x5e/0x90
   device_del+0x1ea/0x350
   device_unregister+0x1a/0x60
   thermal_zone_device_unregister+0x1f2/0x210
   pkg_thermal_cpu_offline+0x14f/0x1a0 [x86_pkg_temp_thermal]
   ? kzalloc.constprop.2+0x10/0x10 [x86_pkg_temp_thermal]
   cpuhp_invoke_callback+0x8d/0x3f0
   cpuhp_down_callbacks+0x42/0x80
   cpuhp_thread_fun+0x8b/0xf0
   smpboot_thread_fn+0x110/0x160
   kthread+0x101/0x140
   ? sort_range+0x30/0x30
   ? kthread_park+0x90/0x90
   ret_from_fork+0x25/0x30

This patch moves the kfree calls to clean up the dynamic attributes to
the thermal_class's thermal_zone_device release function.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Tested-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Jacob von Chorus <jacobvonchorus@cwphoto.ca>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

drivers/thermal/thermal_core.c

@@ -799,6 +799,11 @@ static void thermal_release(struct device *dev)
 	if (!strncmp(dev_name(dev), "thermal_zone",
 		     sizeof("thermal_zone") - 1)) {
 		tz = to_thermal_zone(dev);
+		kfree(tz->trip_type_attrs);
+		kfree(tz->trip_temp_attrs);
+		kfree(tz->trip_hyst_attrs);
+		kfree(tz->trips_attribute_group.attrs);
+		kfree(tz->device.groups);
 		kfree(tz);
 	} else if (!strncmp(dev_name(dev), "cooling_device",
 			    sizeof("cooling_device") - 1)) {
@@ -1305,10 +1310,6 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 
 	thermal_zone_device_set_polling(tz, 0);
 
-	kfree(tz->trip_type_attrs);
-	kfree(tz->trip_temp_attrs);
-	kfree(tz->trip_hyst_attrs);
-	kfree(tz->trips_attribute_group.attrs);
 	thermal_set_governor(tz, NULL);
 
 	thermal_remove_hwmon_sysfs(tz);
@@ -1316,7 +1317,6 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 	idr_destroy(&tz->idr);
 	mutex_destroy(&tz->lock);
 	device_unregister(&tz->device);
-	kfree(tz->device.groups);
 }
 EXPORT_SYMBOL_GPL(thermal_zone_device_unregister);